1. Field
The current disclosure relates to address resolution for networked virtual machines (VMs), including, without limitation, those residing in massive data centers where VMs can migrate from one system to another while needing to maintain their network connections after migrating.
2. Background
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Massive data centers may concurrently serve hundreds of thousands of VMs. VMs are hosted on interconnected physical devices which may be thought of, more generally, as access segments. Multiple access segments communicate with each other by way of a network or the like which may be understood, more generally, as an interconnection layer. Devices that interface access segments with the interconnection layer may generally be understood to be edge devices. A VM on one access segment may thus send communication messages to another VM on a different access segment. This, however, requires knowledge of the other VM's address.
The complexity of requirements for massive data centers is magnified because of the operational factors involved. Take, for example, the just-mentioned situation where a first VM in a first access segment needs to learn the layer-2 address of a second VM. As one step of establishing communication, the first VM broadcasts an address resolution protocol (ARP) request (or Neighbor Discovery (ND) protocol request). The purpose of the broadcast request message is to request the layer-2 network address of the second VM. As such, when a plurality of access segments exists, such ARP/ND broadcast request messages are communicated via the interconnection layer to multiple access segments, even those to whom the second VM is not a member. The extent to which such broadcast messages are sent to various access segments may be thought of, generally, as a broadcast domain.
In massive data centers networked as described above, one attractive feature is to allow virtual machines to move from one access segment to another, all the while keeping the VM's layer-2 and layer-3 network addresses unchanged after migration. One side effect of this feature, however, is that, for ARP and ND protocols or the like, the layer-2 broadcast domain potentially scales up significantly since a virtual machine may migrate to any access segment interfaced with the interconnection layer.